Empty array in c++ shows absurd behavior

Question

The code:
int arr[] = {};
int n;
n = 7;
arr[0] = 15;
cout << n;

gives output:15
Why not 7 ?

AndersK · Answer

You can't do dynamic arrays like that in C++, the size needs to be known at compilation and cannot change dynamically for native arrays, instead use std::vector.

#include<vector>

std::vector<int> arr; 
arr.push_back(15);
...

alt.

#include<vector>

std::vector<int> arr{15};

Itay · Answer

The first line in your code creates an array of size 0.
The next variable in the memory is n, and that's why your program overrides it.
You need to fix your first line to:
int arr[1] = {};

Like people mentioned in the comments above, it does in fact depend on your compiler.

Empty array in c++ shows absurd behavior

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